| 摘要 |
PURPOSE:To utilize negative pressure pulsation generated in an exhaust system to improve scavenging effect and provide high output in a device for opening and closing an exhaust valve by opening again the exhaust valve a predetermined period of time after the exhaust valve is closed. CONSTITUTION:Lubricating oil is adapted to have high pressure by a pump 20 driven by an engine and stored in an accumulator 19. The high pressure oil is supplied to a distributing valve 18 in synchronization with the rotation of the engine and to hydraulic actuators 15, 14 for intake and exhaust valves 2, 1 in a predetermined timing. A controller 30 controls opening and closing timing for intake and exhaust valves in response to the signals of a load sensor 31 and a rotational frequency sensor 32. An exhaust valve 1 is opened a predetermined period of time after it is closed to deduce the period in which negative pressure pulsation is generated in an exhaust port 11 to act on the port from the rotational frequency and load of the engine, and opened at that period.
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